A model-free estimation for the covariate-adjusted Youden index and its associated cut-point

Tu Xu, Junhui Wang, Yixin Fang

Research output: Contribution to journalArticlepeer-review

17 Scopus citations


In medical research, continuous markers are widely employed in diagnostic tests to distinguish diseased and non-diseased subjects. The accuracy of such diagnostic tests is commonly assessed using the receiver operating characteristic (ROC) curve. To summarize an ROC curve and determine its optimal cut-point, the Youden index is popularly used. In literature, the estimation of the Youden index has been widely studied via various statistical modeling strategies on the conditional density. This paper proposes a new model-free estimation method, which directly estimates the covariate-adjusted cut-point without estimating the conditional density. Consequently, covariate-adjusted Youden index can be estimated based on the estimated cut-point. The proposed method formulates the estimation problem in a large margin classification framework, which allows flexible modeling of the covariate-adjusted Youden index through kernel machines. The advantage of the proposed method is demonstrated in a variety of simulated experiments as well as a real application to Pima Indians diabetes study.

Original languageEnglish (US)
Pages (from-to)4963-4974
Number of pages12
JournalStatistics in Medicine
Issue number28
StatePublished - Dec 10 2014
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Epidemiology
  • Statistics and Probability


  • Diagnostic accuracy
  • Margin
  • Receiver operating characteristic curve
  • Reproducing kernel Hilbert space
  • Youden index


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